In the manufacturing field of semiconductor devices, there have been many attempts to increase the integration of semiconductor devices by making the semiconductor smaller. Also, recently, attempts are being made to increase the integration per unit area by stacking a semiconductor device, which is referred to as three-dimensional (3D) mounting.
A plurality of semiconductor devices (chips) stacked in a vertical direction include an electrode that is formed through a substrate and thus the semiconductor devices (chips) are electrically connected to one another via the electrode. When the electrode penetrating the substrate is formed, an insulating film is formed in a hole formed in the substrate, and only the insulating film formed in a bottom portion of the hole and not the insulating film formed on a side wall portion of the hole, is removed so as to expose a wiring unit (electrode pad) formed in a surface opposite to the insulating film formed in the bottom portion.
Next, Ar plasma is irradiated to clean, for example, to remove an oxide film formed on a surface of the wiring unit (electrode pad) exposed by a bottom portion of the hole, and then a conductive metal is embedded in the hole, thereby forming an electrode penetrating two sides of the substrate.
As described above, in order to remove only the bottom portion and not the side wall portion of the insulating film formed in the hole, the hole is formed with a tapered shape, a tape is attached to a surface of the substrate, a small hole having a diameter smaller than that of an opening of the hole is punched in the tape to correspond to the hole, and the bottom portion of the insulating film formed in the hole is etched via the small hole formed in the tape (refer to Patent Reference 1).
In the above-described method of manufacturing a semiconductor device, to perform a cleaning process to remove the oxide film formed on the wiring unit exposed by the bottom surface of the hole after removing the insulating film formed in the hole, a process for irradiating plasma of an inert gas, such as Ar plasma, may be performed. However, when an organic film such as a polyimide film is used as the insulating film formed in the hole, if such a cleaning process is performed, the organic film may be damaged due to the Ar plasma, and thus an insulating property may be degraded.